Health Monitoring of Bolt Looseness in Timber Structures Using PZT-Enabled Time-Reversal Method

Abstract

A prestressed bolt connection is one of the crucial connection types in timber structures. The daily checking and maintenance of bolt connections have to be carried out in order to avoid the collapse of timber structures due to bolt looseness. Real-time health monitoring of bolt connections can not only reduce the daily maintenance cost of timber structures, but it can also avoid property loss and casualties by giving early warning if the bolt connection is loosened in timber structures. This paper proposes a method of prestress monitoring of bolt joints in timber structures by pasting lead zirconate titanate (PZT) patches on the surface of timber structures, and the time-reversal method is applied to denote the connection status of bolts in timber structures. The prestress loss index of timber structural bolts based on wavelet analysis is designed to quantify the bolt looseness of the timber structure. The experimental timber specimen was fabricated consisting of two timber panels, one bolt, and two PZT patches. One of the PZT patches acted as an actuator to emit the stress waves, and another one acted as a sensor to receive the stress wave propagating through the connection interface. The experimental results showed that the amplitude of the focused signal increases significantly with the increase of the prestress value of the bolts, which verify that the proposed method can be utilized to monitor the looseness of bolts in timber structures. The analysis results of the focused signal is proof that the prestress loss index of timber structural bolts designed based on wavelet analysis can reflect the looseness of timber structural bolts.

Detection Method for Bolted Connection Looseness at Small Angles of Timber Structures based on Deep Learning

“…Based on this technique, Xu et al [ 6 ] optimized the gathering approach of the ultrasonic signal to improve the accuracy and to expand the range of sensitivity. Zhao et al [ 7 ] applied this method on looseness testing of bolted connections on a wood structure, and put forward the loss index of the preload of a bolt to describe the looseness of a bolted connection in wood structures. Zhang et al [ 8 ] developed a bolt looseness detection method based on audio classification.…”

Real‐Time Monitoring of Timber‐Surface Crack Repair Using Piezoelectric Ceramics

“…Active health monitoring technology is commonly used to monitor the damage and early strength development of concrete structures [43][44][45][46][47][48][49][50][51], the interfacial debonding of structures [52][53][54][55][56][57], the damage of reinforced concrete structures [58][59][60][61], the looseness of thread connections [62], soil compactness and freezing-thawing process [63,64], and the damage of metal thin plates [55,65]. In recent years, the health monitoring technology based on piezoelectric ceramics has also played an important role in the field of timber structure health monitoring, including monitoring the damage degree of timber structure [66][67][68][69], the change of water content [70], the connection state of components [71,72], and the damage state of timber specimens during loading [73,74]. The results of these studies demonstrate the effectiveness, superiority, and accuracy of this method in the health monitoring of timber structure.…”

Loosening of Bolted Connections under Transverse Loading in Timber Structures

“…For the detection of bolt loosening, a bolt connection model based on fractal contact theory was constructed by Huo [7], piezoelectric transducers were adopted to monitor bolt loosening waves. Zhao [8] proposed a method to monitor the pretension of bolted connections in timber structures by pasting lead zirconate titanate (PZT) patches to reflect the looseness of bolts. Wang [9] compared the antiloosening effect of different composite bolted forms under high temperature vibration environment through a random vibration test.…”